Treatment of Type 2 diabetes — one of the country’s biggest health challenges — could be improved dramatically as a result of two related discoveries made by San Diego scientists.

The findings, derived from studies of mice, point to new paths to overcoming insulin resistance, in which this critical hormone becomes less effective in lowering blood sugar levels. Insulin resistance increases the risk of heart disease, obesity and kidney, eye and nerve damage.

Insulin resistance is a hallmark of Type 2 diabetes and a related condition called metabolic syndrome. These diseases are increasing in prevalence, and threaten to add billions to the cost of U.S. health care.

Moreover, the studies may lead to new methods of controlling inflammation, an underpinning of other chronic diseases such as cancer.

While the discoveries must still be tested in people, what excites researchers is that they point to previously unknown targets for developing new drugs. So the problems that have stymied development of better treatments may no longer impede progress on a growing health burden.

About 29 million Americans had diabetes in 2012, and 90 percent to 95 percent of those cases were Type 2, according to the Centers for Disease Control and Prevention. Diabetes cost the U.S. a total of $245 billion. Of this, $176 billion represent direct medical costs. Another $69 billion constitute indirect costs of disability, lost work and premature death.

Type 1 diabetes has a straightforward cause: a lack of insulin. The remedy, supplying insulin, is equally obvious. But finding the causes and treatment of Type 2 diabetes and its related conditions are more difficult. Diet and a lack of exercise are two major culprits; reducing weight is strongly correlated with overcoming insulin resistance. However, reducing weight is notoriously difficult for many people.

Ethnic factors also play a role, according to the centers. The incidence of diagnosed diabetes in those 20 or older ranges from 7.6 percent in non-Hispanic whites, to 13.2 percent in non-Hispanic blacks and 15.9 percent in American Indians.

The new therapies identified in the studies led by Salk Institute and UC San Diego researchers appear to avoid these side effects.

— A well-known protein efficiently restores insulin sensitivity when injected into diabetic mice, according to a study published Wednesday in the journal Nature. Ronald M. Evans of the Salk Institute was principal investigator for this study.

— Another study, published July 6 in Nature Medicine, reported that a small molecule potently mimics the action of “heart-healthy” omega-3 fatty acids. The molecule stops inflammation and a cascade of other events that lead to insulin resistance. Jerrold Olefsky of UC San Diego led that study.

Complementary

The studies complement each other, Evans said. He and Olefsky were co-authors on both studies.

“If we want to treat the problem, we have to understand the science,” Evans said. “And that’s why these two papers are very important. They represent new discoveries that we didn’t even know a couple of years ago. I think they’ll have a very good chance of getting into the clinic rapidly.”